I am using version 1.3 of python-snap7 to read data from an S7-300 PLC. Reading out the data works perfectly, both on inputs, flags and data blocks. However, as soon as I execute the function 'get_cpu_info()', the PLC crashes and all LEDs starts to flash. To bring the PLC 'back to life', it must be completely powered down.

Python version: 3.10.6
Python Snap7: v1.3

Reproducible on the following PLCs

• CPU 315F-2 PN/DP 6ES7 315-2FJ14-0AB0 v3.2
• CPU 317F-2 PN/DP 6ES7 317-2FK13-0AB0 v2.6.7

Message buffer PLC after restart

Number | Time | Date | Event
1 | 12:46:10:971 pm | 20.09.2023 | Mode transition from STARTUP to RUN
2 | 12:46:10:967 pm | 20.09.2023 | Request for manual warm restart
3 | 12:46:10:763 pm | 20.09.2023 | Mode transition from STOP to STARTUP
4 | 12:45:58:008 pm | 20.09.2023 | Memory reset executed
5 | 12:45:50:993 pm | 20.09.2023 | STOP caused by CPU memory management
6 | 12:45:50:993 pm | 20.09.2023 | Power on backed up
7 | 12:45:50:993 pm | 20.09.2023 | Illegal module: replace module and reset memory
8 | 12:42:29:983 pm | 20.09.2023 | DEFECTIVE: internal system error
9 | 11:45:21:496 am | 20.09.2023 | Mode transition from STARTUP to RUN
10 | 11:45:21:492 am | 20.09.2023 | Request for manual warm restart

code snippet

        try:
            for j in range(self.nr_clients):
                self.client[j].set_connection_type(0xFD)
                self.client[j].connect(address=self.config.s7_ip, rack=self.config.s7_rack, slot=self.config.s7_slot)
                await asyncio.sleep(1)

            test = self.client[0].get_cpu_info()    # EXECUTE ==> CRASH!
            self.connection_finished = True
        except Exception as ex:
            self.logger.error(f'Client: Error while open the S7 connection to {self.config.s7_ip} ID: {j}! [{ex}]')